Electric-resistance melting-furnace.



UruTE-D sTAirEs PATENT oFFioEJ AUoUs'i` voELKER, or BEUEL, NEAR BONN,GERMANY.

ELECTRIC-RESISTANCE MELTIG-FURNAE.

specification of Letters Patent.. Patented Jan. 21, 1913.

pplication filed February 18, 1911. Serial No. 609,468.

TQ all whom t may concern Be it known that I, AUGUST VonLKnn, a subjectof the King of Prussia, German Emperor, lresiding at 77a'Siegburgerstrasse, Beuel, near Bonn, in the `Empire of Germany, haveinvented a new and useful Electric-Resistance'Melting-Furnace, of whichthe following is a specification.

Quartz melting furnaces are known, consisting of a carbon core in theshape of a rod, which is in closed on the central part of its length bya concentrically arranged tubular shell, leaving an annular spacearoundA said core, and which willxin consequence of an electric currentsent through it, fuse the arenaceous quartz filling out said annularspace progressively from the inside to lthe outside. these melting'furnaces consisty in lit being possible, indeed, to make the outerportions of the quartz body produced in the annular space, cohere, Iandeven to create on it a thin glaze-like fused film of the shellgenerally7 made ofl carbon surrounding the .central heating core; it is,however, not possibleito lso thoroughly fuse the interior of the quartzcharge so that. a product is obtained of a uniform structure throughout,although it is of the'greatest importance forthe subse# quent treatmentof the quartz body and the quality of the articles made therefrom,

My invention relates to improvements 'in such lelectric furnaces,whereby 'the said `One `improvement consists in connecting the 'outershell at one endby means of a conductor in series with the inner corepass- Ving through the shell.

Another improvement consists in longitudinally adjustable connections onboth the s'hell and the core for the conductor between j vthe shell andthe core at the said one end and for the current cables at the otherend.

A-third improvement consists inthe longitudinaladjustment of the' corerelatively to .the shell. Then the electric current will firstlongitudinally pass through the shell and then by means of the conductorthrough the core. Thereby it is obtained, that,-al;

though at first,` that is at the commencement of the furnace, theoutside o f the working shell Ywill be heated, even if not up' to the:melting temperature of the quartz, and with `it the adjoining vportionof thequartz charge,the.current will, according the duration of thepassageof the cur- -The drawbacks of` rent and the progress of thefusion; gradually pass, besides in a longitudinal, lalso in a radialdirection from the shell tothe core thro-ugh the charge becomingconductive in consequence of the fusion, so that a final product ofhomogeneous structure is obtained. This process may bel regulated bygradually shiftingthe points of connection on the `shell and' the coreas thereby the re- 65 sistances and also .the heating effect may bevaried.

lt is true, electric melting furnaces `are known, `ir which aCrucible-like melting chamber, closed below, is employed as seriesresistance for 'a centrally arrangedv live heating core in contact withthe bottom. But with such arrangement it is intended to keep the wallsof the Crucible cold and save thev latter', by increasing the 'heatingof the 75 tional form of the vinvention forming the subject matter ofthe present application is exemplified. It must be understood, that theinvention shall not be limited to this one constructional form only.

It consists of a furnace bodyia supportl ed on trunnions turning onstands l), and 1s lined with insulating material. Into said body a isfitted a carbon tube c in such a manner that it projects `at both endsfrom the furnace. closed by suitable disks (not shown) Aof in' sulatingmaterial and providedwith a central hole. Where so preferred, of coursein otherwords they may be provide shoulders adapted to bear against theannular end faces ofthe. tube c, 'so that they may be Vinserted anddetached Y easily. Through the central holesof these two' disks.

these disks may be set off on the periphery,

`a comparatively thin carbonior graphite rod 106 Y d is passed and thespace between said rod,

the inside of the shellc and said two disks istilled with arenaceous orother raw quartz. The two ends of the carbon bodies al and ccarrydisplaceable contact rings f1, f2 and e1, 110

e2 respectively made of the same material. Terminals g1, 1 are providedon the contact' They are therefore more or less un- 80 The ends of thetube c are with .rings e1, fl/at the lower end for -introducing l -thecurrent to and'letting it out from the shell tube 'c orthe heating lcored respectively, while similar terminals g2, i2 are providedon thecontact rings e2,-.f2 'at the upper end and-.al bar la, is 'provided forconnecting v the yterminals g2, .2 at various heights by y enters at e1intotheshell c, flows through' "mcans'ofa series of holes and forserving as Viii/conductor, 1t conducting the' current from gft/tod. f

While the furnace is-working the current 'the latter'and the bridge barh into. the

.core d. and `fromthe core d into the conduc tor connected tothe.terminal 1.- At first' c' and igher temperature of core the charge,whilethe quartz along the inside shell c will coherev andcake.- lVi'ththe pro-V gressing fusing of the 'charge thesame will become conductive,in consequence o f which 'the'j current willno more flow through thebodies c and d in .a longitudinal direction only,bu't will also passin--a radial direction through the charge, purify it and fuse it inalfomogeneous manner. The resistance of the carbonbodiesc, dvarying-with'thedura# `tion et the passage of the current-andthe- `.30

progressingl fusion, may be compensated or also .an intentional'variation oflthese re-f sistances may,jfor the purpose of Aobtaininga.more rapid Afusion 'and urifcationof cer,-`

' 'tain parts of the quartz ch 35.

arge, be produced by changing the position of theI admission and outletterminals il, i2 'and g1, g2 re; spectively by .displacing the contact'rings v f2 and 91,62 von their respective carbon bodies d and c,so-that the length of the pathofthe current. land the heating effecto-iithe parts' ofz the charge penetrated may be easily regulated.

'I claim: 1. An electric melting furnace, in which a thin live.resistance heating core' 1s concentrically surrounded at agiven'distance 'by a 4tubular shell for between the core and the shell,the' said inliig a 'space for the char e' tubular 'shell connected byafcoiiductor as a'.

5ol' core, whereby the current entering at one series resistancein'series with the'heating end (if said' 'shell will flow longitudinallythrough 'the same,`.then'pass into' said conductor connecting the shellwith the core and' finally come out atfthefother end of the core thetube at one end and connected with an inlet -lating 'material providedlwithcentral holes,

at both ends of. said tube, a thin carbon rod guided in the holes ofsaid twocovers and projecting therefrom at both ends, whereby an annularspace for the charge is formed between said' rod, the insidebf said tubeand said twocovers, a contact ring ad'ustable on terminal, a -similarcontact ring adjustable on the tube at the other end and conductivelconnected with a bridge bar provided with,

holes, any adjustable contact ring on the correspondingend of the carbonrod and conductivelyconnecte'd with said bridge .bar and ladjustableythereto by means of said holes, i

and an' adjustable contact ring at Athe other l 'e'nd offsaid carbon'rod connected to a`cond 'uctor leading-olf the current. d0 "3.1A1i'electric melting furnace consisting l .of a furnace lbody supported ontrunnions turningon stands, and lined with insulating material, a'carbon tube in said body project. ing at 'both ends,l two removablecovers of insulating material provided with central holes at both endsof said tube, a thin car- 'bon rod guided in the holes of said twocovers -and projecting therefrom at both ends, whereby an'annular spacefor the charge is formed between sa'id'rod, the inside of said' tube andsaid two covers; a-'contact ring adjustable on the tube-'at one end andconnected with an in'let terminaba similar contact ring adjustable onthe tube at'the other end 95 and conductively connected withav bridgebar provided with holes, an adjustable contact ring. on thecorresponding end yof the carbon Lrod and conductively connected withsaid bridge bar and adjustable thereto by means of said'holes, and anadjustable contactring lat the other end of said .carbon rod connectedto aconductor leading off the current. a In testimony whereof I heretoaix my 105 signature ini the presence of two witnesses.-

. AUGUST VQELKER; s In presence o-f- N IKoLAUs Mmmm, Louis VANDORY.

